ELECTRICAL DOUBLE-LAYER ON RENEWED IRON ELECTRODES IN SOLUTIONS BASEDON A NUMBER OF ORGANIC-SOLVENTS

Dependences were obtained of the current and impedance component trans ients on the potential for Fe electrodes renewed by cutting in the sol utions based on certain organic solvents: tetra-methylurea, dimethylfo rmamide, dimethylacetamide, N-methylpyrrolidone, hexamethylphosphortri amide, dimethylsulfoxide (DMSO), and acetonitrile (AN). It was found t hat the renewed iron electrode in LiClO4 or KBF4 solutions in a certai n potential region behaves in the first approximation as an ideally po larizable electrode (with the exception of DMSO and AN solutions). The values of potentials of zero charge (pzc) of Fe were determined from the capacitance minimum in dilute electrolyte solutions. The relations hip between the double-layer capacitances corresponding to the positiv e and negative charges strongly depends on the solvent nature. A simil arity was found in the behaviour of Fe and Pt electrodes, which is ass ociated with the chemisorptive interaction between these metals and or ganic solvent molecules. Literature data on the Fe pzc in aqueous solu tions are analyzed in comparison with the data for organic solvents an d from the standpoint of the correlation with the work functions W of metals. It is concluded that the values of Fe pzc obtained earlier by Leikis, Rybalka, and Zelinskii for renewed Fe electrodes in aqueous el ectrolyte solutions correspond most closely to the active iron surface free from any oxides. Copyright (C) 1996 Elsevier Science Ltd